The use of agricultural substrates to improve methane yield in anaerobic co-digestion with pig slurry: Effect of substrate type and inclusion level

Anaerobic co-digestion of pig slurry with four agricultural substrates (tomato, pepper, persimmon and peach) was investigated. Each agricultural substrate was tested in co-digestion with pig slurry at four inclusion levels: 0%, 15%, 30% and 50%. Inclusion levels consisted in the replacement of the volatile solids (VS) from the pig slurry with the VS from the agricultural substrate. The effect of substrate type and inclusion level on the biochemical methane potential (BMP) was evaluated in a batch assay performed at 35 °C for 100 days. Agricultural substrate’s chemical composition was also analyzed and related with BMP. Additionally, Bacteria and Archaea domains together with the four main methanogenic archaeal orders were quantified using quantitative real-time TaqMan polymerase chain reaction (qPCR) at the end of the experiment to determine the influence of agricultural substrate on sludge’s microbial composition. Results showed that vegetable substrates (pepper and tomato) had higher lipid and protein content and lower carbohydrates than fruit substrates (persimmon and peach). Among substrates, vegetable substrates showed higher BMP than fruit substrates. Higher BMP values were obtained with increasing addition of agricultural substrate. The replacement of 50% of VS from pig slurry by tomato and pepper increased BMP in 41% and 44%, respectively compared with pig slurry only. Lower increments in BMP were achieved with lower inclusion levels. Results from qPCR showed that total bacteria and total archaea gene concentrations were similar in all combinations tested. Methanomicrobiales gene concentrations dominated over the rest of individual archaeal orders.     

County-level prohibition and alcohol-related fatal motor vehicle accidents

The 50 states and the District of Columbia were grouped according to whether or not they had county-level alcohol prohibition. Several motor vehicle fatality rates were calculated for each type of jurisdiction, including the single-vehicle fatality rate (an index of alcohol-related motor vehicle accidents). In all cases, motor vehicle fatality rates for drivers in states with county-level prohibition were significantly greater than in nonprohibition states. This suggests that drivers residing in counties with prohibition are compelled to drive to adjacent counties or states to drink and consequently have increased involvement in motor vehicle accidents.     

Structure of and relationships within and between the littoral,rock-substrate fish communities off four islands in the Canarian Archipelago

A total of 577 visual surveys (each of 5 min in duration and 100 m² in area) were conducted throughout 1990 and 1991 at 32 locations off four Canary islands (i.e., Alegranza, Fuerteventura, Gran Canaria and Tenerife) with the objects of describing the coastal fish community, comparing the differences in the fish fauna within and between these islands, and determining the biotic and abiotic factors related to the structure of the fish communities. A total of 76 species were recorded; the most common were Abudefduf luridus, Canthigaster rostrata, Chromis limbatus, Sparisoma cretense and Thalassoma pavo (94.28, 86.48, 52.34, 73.31, and 94.10% frequency of occurrence, respectively). The abundance and average size of the commercially important species was greater in those locations where there was less fishing pressure. The stepwise linear regression models were capable of explaining only a low amount of variation in the dependent variables (i.e., number of species, number of individuals, average size and species diversity) of the fish community. The independent variables recorded were date, time of day, depth, slope of the substrate, substrate type, percentage of sand, percentage of algae, algal height, number of sea urchins (Diadema antillarum) and the individual islands. An ANOVA, using the islands only as independent variables, indicated that each island contributed significantly to the variation in the four dependent variables and there were significant differences among the islands. Detrended correspondence analysis (DCA) and a two-way indicator species analysis (TWINSPAN) determined associations between species and environmental attributes of the survey locations. The patterns in the TWINSPAN analysis indicated that localities had faunal resemblances based on the island off which where they were located.